Epidemiology Branch (EB)

EB Research - Reproductive Epidemiology

The BioCycle Study: A Longitudinal Study of the Estrogen and Progesterone Effects on Biomarkers of Oxidative Stress and Antioxidant Status During the Menstrual Cycle

Study Design

The BioCycle Study is a prospective cohort study completed at the University at Buffalo and offers a unique and comprehensive assessment of menstrual cycle function. The primary goal of the BioCycle Study was to better understand the intricate relationship between reproductive hormone levels and oxidative stress during the menstrual cycle. Multiple markers of oxidative stress, reproductive hormones, inflammation, and metabolic biomarkers were measured in a cohort of 259 women of reproductive age over the course of two menstrual cycles. Fertility monitors were utilized to time the subjects' visits to ensure appropriate timing of biospecimen collection. Additional information regarding diet, lifestyle, and physical measurements was obtained throughout the study via standardized questionnaires, anthropometric assessments, and daily diaries. Participants were highly adherent to the study protocol, with 94% of all women completing seven or eight visits per cycle.

Important Research Findings

Since completion of the study much progress has been made in the analysis of the BioCycle Study data. To date, over sixty papers have been published. We have shown that metabolic markers such as markers of oxidative stress, lipoprotein cholesterol, inflammatory and glucose metabolism markers, and uric acid vary significantly across the menstrual cycle among healthy, regularly cycling women. These findings have implications for clinical practice (i.e., certain doctor visits should be timed to menstrual cycle phase) and for study designs including women of reproductive age.

The BioCycle Study has also contributed substantially to the field of nutritional, environmental, and social epidemiology. We have thoroughly assessed varying dietary patterns (e.g., Mediterranean Diet), food/beverage intake (e.g., whole grains, fiber, and sweetened soda), macro/micronutrients (e.g., fiber, folate, carotenoids, isoflavones, and fructose), environmental factors (e.g., blood cadmium, lead, and mercury levels) and psychosocial stress and depression in relation to premenopausal women’s reproductive and cardio-metabolic health. Overall, these papers have been influential in describing not only the short-term impact of a healthy diet and lifestyle on hormonal function and markers of menstrual cycle dysfunction (e.g., anovulation, luteal phase deficiency, and abnormal menses) but their potential long-term impact on chronic disease risk.

The team intends to build upon its current findings from the BioCycle Study to fill critical research gaps in its quest to answer important public health questions for women of reproductive age. Planned analyses will evaluate additional diet, lifestyle, environmental, and psychosocial factors, focusing on their interplay with endocrine function and biomarkers of chronic disease.